Eleoteic fuse oe detonatoe



(No Model.)

P. WARD 85 E. M. GREGORY.

ELECTRIC FUSE OR DETONATOR.

Patented Jan. 12, 1892.

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ELECTRIC FUSE OR DETONATOR.

SPECIFICATION forming part of Letters P Application filed May 13, 1890.

atent N0. 466,856, dated January 12, 1892.

Serial No. 351,694. (No model.)

To all whom it ntay concern:

Be it known that we, PAUL \VARD and EDWARD .MAMMATT GREGORY, residing atLondon, England, have invented an Improvement in the Method ofConstruction of Electrical Fuses and Detonators, of which the followingis a specification.

Our invention relates to improvements in the method of manufacturingelectrical fuses and detonators, and has for its object to provide afuse which by its accuracy of position of the detonating-wires shall beuniformly sensitive.

To carry out'our invention we employ a bent or closed armature of wire,by which ignition is effected electrically, composed of either insulatedor uninsulated wire of any suitable conducting metalsuch as copper oriron-and termed a safety-armature, because formed in a loop which isineffective to produce ignition until the said loop has been broken orcut and each side of the loop has been separated from metallic contactwith the other.

From the method of construction hereinafter described it will be seenthat we form the insulator, the wires, and the receptacle for holdingthe priming composition, all combined with accuracy within special gagesor tools, so that an absolutely uniform arrangement of the wireterminals is insured, both in the amount of surface exposed and in thedistance of their-separation from one another, whereby the article ismuch simplified and cheapened, and all the fuses may be ignited withcertainty and with extreme sensitiveness by a definite small current ofelectricity and the complete fuses protected from any climaticdestructive influences.

In orderthat ourinvention may be the better understood, we now proceedto describe the same in relation to the drawings hereunto annexed,reference being had to the letters marked thereon.

Like letters refer to like parts in the various figures.

Figure 1 shows in side and end elevation and in plan the slab or tool inwhich the fuse-plugs are manufactured. Fig. 1 is a side and end view ofthe plug used in c011- junction with the above table. Fig. 2 shows thewire armature in position ready for the formation of the insulatingplug. Fig. 3 shows the Wire armature with the insulatingplug formedthereon. Fig. 4 shows the completed fuse covered by protective coatings.

WVe employ a slab of metal A (shown in side and end elevation and planinFig. 1) or other material, which is drilled through from face to facewith holes about one-eighth of an inch in diameter, or of such diameterasis suitable for the fuse required. This slab is supported by feet F ofsuchaheight that plugs of metal or other material inserted into theholes in the slab rest on the table supporting the whole, so that theplugs do not reach the upper surface of the slab A by, say, one-fourthof an inch. These little plugs, as shown at 9, Fig. l", are dome-shapedat their upper ends and have two fine holes drilled to a small depth(say one-fortieth of an inch) in their domed ends as close together asis practically convenient without their coalescing. Into these two holesin the said plug are inserted the two free ends of a smallhair-pinshaped wire loop E, so as to hold the two free ends of the wireloop in a certain definite position both as regards length and widthapart in the hole in which the plug of metal is contained. hen all theholes inthe slab and plug are occupied in a similar manner, theremaining spaces above the dome-shaped plugs containing the wires arethen filled up with a composition consisting, by choice, of

an intimate mixture of Whitening and glue or whitening and gum or othersuitable insulating ingredient to render the said compositionwater-proof, and in order to make the said composition both heat anddamp proof we mix therewith a suitable quantity of the powder derivedfrom the calcination of peat. When the liquid part has evaporated orbeendriven from the mass contained in the said holes, the plugs are pushedup from the bottom and the wires, surrounded by the compositionbefore-mentioned, are taken out, the result being cup-shaped cavities,as in the non-conducting plug shown at B, Fig. 3, with the two ends ofthe wires projecting a certain definite Width apart and lengththereinto, but completely insulated from each other. Any furthermoisture may be driven off by a gentle heat.

A suitable quantity of explosive compound (priming material) is nowplaced into the cupshaped cavity and the same is laid aside to dry. Asuitable quantity D, Fig. 4, of the composition of which the piece B inwhich the cup-shaped cavity is formed (before described) is caused tosurround the plug 13 and the priming material,or to cover the primingmaterial only, and the Whole may then (if considered necessary) beprotected by dipping into just-melted paraffine or other wax andafterward in Portland, Roman, or other hard cement, and is shown at C,Fig. at; or the insertion of a second layer D of the composition of theplug B, in which the cavity is formed may be dispensed with and the fuseprotected with the paraffine or other Wax and cement. 1

By the before-described method We form a complete fuse. The whole maythen (if con sidered necessary) be coated over with a fusible alloy oflow-melting temperature, or even with lead, by immersion in the moltenmetal.

If we wish to make a combined fuse and detonator, we previously todipping the fuse into the cement or other protective coating, asaforesaid, but subsequently to immersing it in the melted wax, insertinto the cup on the top of the Wax a quantity of detonating material.This combined fuse and detonator is then protected in the manner abovemen tioned.

Having fully described our invention, what we desire to secure byLettersPatent is The process of manufacture of an electrical fuse or detonatorby which the ends of the detonating-wires are held in recesses of ametal plug-tool at a desired and definite distance apart, the said plugbeing inserted into a small cylindrical chamber in a block, thedetonating-wires being then permanently incorporated in a plug ofnon-conducting ma terial formed to exact size in the said chamber, so asto allow the ends of the wires to project slightly into a cavity to holdthe priming composition, and the completed fuse being then dipped firstinto melted paraffine or other wax and then in Portland, Roman, or anysuitable cement.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

PAUL WARD. EDWARD MAMMATT GREGORY.

itness:

REGINALD W. JAMES, RICHARD A. HOFFMANN.

